wa em a ee ee ee ~ 2. 7 important mode of entry of radiolodines in fallout. In sources of drinking water for major urban populations the delay between rainfal} and consumption usually assures decay of ifodine-131 to an insignifi ‘ant level. In addition dilution and other factors are effective in reducing the fall- out concentration, Fresh food becomes, then, the main source of iodine-131 fr environment. For most foods the time delay between harvest and is sufficient to reduce fodine-131 to an insignificant level. generally the case with fresh milk for which the time between p m the consumption his is not oduction and consumption averages about 3 days in the United States. Th re is some evidence suggesting that consumption of some locally grown vege ables and produce, even after washing and normal home preparation, could contribute to the diet amounts of the order of those from fresh However, there is no question but that fresh milk is by far the tributor of iodine-131 to the United States population as a who Relatively little information is available on the consumpt cow's milk by people in various age groups. The most detailed udy now available was completed in 1962 and presents per capita consump on by age and sex.» During the first few months of life, the intake of resh cow's milk may be zero for infants who are breast-fed or given formul based on processed products, From the survey study, the average for chi ren under one year of age was about 0.5 liter per day which was maintaine until late in teenage after which a gradual decline occurred. For adult es and females in the population-at-large averages were 0,35 and 0.25 iters per day respectively. The range extended from persons consuming no ilk toa group comprising 1 to 10 percent who consumed more than 1 liter er day. Large individual differences were found at all ages. The thyroid gland is unique in its relation to the metaboli pm of Lodine in either stable or radioactive form. Weighing only about 1 to P grams at birth, and 15 to 20 grams in the adult, this gland has a high af Finity for iodine. A normal thyroid will absorb and retain 15 to 30 percenf of a small quantity of ingested iodine, The exact amount retained wi 11 depend, among other things, upon the amount of stable iodine ingested du ring the 3p. H. Wasserman, F. W. Lengemann, J. C. Thompson, Jr., and C. L Comar. "The Transfer of Fallout Radionuclides from Diet to Man," Chapt r 9, in Radioactive Fallout, Soils, Plants, Foods, Man edited by E. Elsevier, 1965. . Fowler, 4Bureau of the Census, Department of Commerce and Division of Radiological Health, Public Health Service, "National Food Consumption Surve : Fresh Whole Milk Consumption in the United States." Radiological Hea Ith Data 4:15, No. 1, 1963. -Bureau of the Census, Department of Commerce and Division of Ra diological Health, Public Health Service, "Consumption of Selected Pood It a in 'U. S. Households."' Radiological Health Data 4:124, No. 3, 1963 DOE ARCHIVES